A conventional electrostatic actuator is adapted to actuate a moving electrode by employing electrostatic attraction, which is acted between electric charges, in such a manner that the electric charges are induced into a fixed electrode and the moving electrode, disposed on an insulating substrate, by applying a voltage to the fixed electrode and the moving electrode. At this time, the moving electrode is moved in such a way to make restoring force of a support member, which supports the moving electrode, being in equilibrium with electrostatic attraction.
FIG. 1 is a view illustrating a conventional cantilever type electrostatic actuator. Referring to FIG. 1(a), a voltage is applied between a fixed electrode 120 and a moving electrode 130 in order to induce electric charges between the fixed electrode 120 and the moving electrode 130, thereby actuating the moving electrode 130 by employing electrostatic attraction to act between the electric charges. At this time, a voltage may be applied to the moving electrode 130 through a support member 140, which is electrically connected to the moving electrode 130, without directly applying the voltage to the moving electrode 130. Since the restoring force of the support member 140 is acted in an opposite direction to that of the electrostatic attraction acting on between the electric charges, the moving electrode 130 is moved toward the fixed electrode 120 up to a point where the restoring force of the support member 140 becomes in equilibrium with the electrostatic attraction.
FIG. 1(b) diagrammatically shows an actuator 100 of FIG. 1(a). In FIG. 1(b), the support member 140 of FIG. 1(a) is represented by a spring for making the moving electrode 130 being spaced apart from the fixed electrode 120 with a specific interval therebetween at a corresponding position.
In order to actuate the actuator 100 at a low voltage, the restoring force of the support member 140 must be designed weakly. However, if the restoring force of the support member 140 is weak, the support member 140 becomes vulnerable to noise and has weak durability. Accordingly, a problem arises because a reliable and consecutive operation is impossible.